The present invention relates to an apparatus and method for improving the effectiveness of a washer fluid, such as that used in a motor vehicle. More specifically, the present invention relates to an apparatus and method for heating a washer fluid in an automobile, where the washer fluid is used for cleaning the windshield, headlamps, or other dirt-collecting surfaces.
The windshield of an automobile requires cleaning at various times to insure clear vision. For this purpose, windshield washer fluid is typically pumped from a reservoir to a pair of spray nozzles directed at the windshield, and the windshield wipers are activated to effect the cleaning process.
A simplified diagram of both a typical automotive cooling system and a typical windshield washer system is depicted in FIG. 1. An engine coolant medium, e.g., ethylene glycol and water, is circulated by a water pump (not shown) through an engine block coolant jacket 100 to a thermostatic control valve 102, which is typically set for a temperature around 190xc2x0 F. Valve 102 outputs a portion of the coolant to a radiator 104 (point xe2x80x9cExe2x80x9d), and the remainder is returned to jacket 100 for temperature control. Radiator 104 dissipates heat from the engine coolant, and returns the coolant at a reduced temperature (point xe2x80x9cFxe2x80x9d) to coolant (water) jacket 100.
Independently, a washer fluid reservoir 106 provides washer fluid at ambient temperature to a washer fluid pump (not shown) on demand from the vehicle operator. When activated, the washer fluid pump directs the washer fluid to a set of spray nozzles 108, which eject the washer fluid against a windshield 110. Simultaneously, windshield wipers are turned on, to implement the windshield cleaning process in conjunction with the washer fluid spray.
However, some types of external detritus, such as ice and insects, can impede the cleaning action of the windshield wipers when used with washer fluid at ambient temperature. Moreover, it is well known that most cleaning solutions, such as washer fluid, are much more effective when heated, and especially so for deicing purposes. Accordingly, it is an object of the present invention to provide a simple and economic apparatus and method for heating the washer fluid in a motor vehicle, in order to improve its cleaning effectiveness.
In accordance with an illustrative embodiment of the present invention, an apparatus and method for heating a washer fluid in a motor vehicle uses the heat from the engine coolant in the motor vehicle. This is achieved by flowing the ambient temperature washer fluid through a coil tubing wrapped around a tube carrying the engine coolant exiting the engine block at elevated temperature. Both the washer fluid tubing and the engine coolant tube are made of thermally conductive material, so that the washer fluid flowing through the coil tubing is heated by the elevated temperature of the engine coolant. The heated washer fluid is then directed against a windshield, or other dirt-collecting surface, such as headlamps.
To further control the temperature of the washer fluid being directed at the dirt-collecting surface, a mixing valve is introduced into the heated washer fluid line. The mixing valve is controlled by temperature sensors which monitor the outside surface temperature of the dirt-collecting surface, and the heated washer fluid temperature. Based on a predetermined desired temperature differential, the mixing valve combines heated washer fluid with ambient temperature washer fluid and outputs a washer fluid mixture at the desired temperature value. This washer fluid mixture is then directed at the dirt-collecting surface.
An illustrative embodiment of the present invention is more fully described below in conjunction with the following drawings.